This invention relates to stabilization of cooked pasta compositions against the development of toxins from pathogenic bacterial contaminants. The stabilized pasta compositions are attained by the incorporation of nisin-containing cultured whey derived from a nisin-producing culture. The cooked pasta compositions of this invention, which include both filled and unfilled pasta compositions, are stable at refrigeration temperatures for 90 days or longer, and preferably for 120 days or longer, and require no further cooking (i.e., the pasta is fully hydrated and only requires warming before serving).
Pasta products are generally shaped dried doughs made from durum or wheat flour mixed with water and, sometimes, eggs and/or milk. Pasta products are generally available as fully dried (generally about 10 percent or less moisture) or refrigerated (generally about 30 percent or less moisture) products.
Such products should, of course, be prepared free of pathogenic organisms, especially toxin-producing anaerobes. Pathogenic organisms that may contaminate food products include, by way of nonlimiting example, Clostridium botulinum, C. perfringens, (Lucke et al., in xe2x80x9cEcology and Control Foodsxe2x80x9d (A. H. W. Hauschild and K. L. Dodds, eds.) Marcel Dekker, New York, 1993, pp. 177-207; Smart et al., J. Appl. Bacteriol. 46, 377-383 (1979); Roberts et al., J. Fd. Technol., 14, 211-226 (1979); Tompkin, Food Technology, 34, 229-236, and 257 (1980); Bryan et al., Amer. Public Health, 61, 1869-1885 (1971); Microbial Ecology of Food Commoditiesxe2x80x94Microorganisms in Foods 6: Blackie Academic and Professional, 1998, p. 115), Listeria monocytogenes, Escherichia coli, Bacillus cereus, Enterococcus faecalis, and similar microorganisms. Among these, spore-forming, toxin-producing microorganisms are of particular concern, because any spores produced by viable cells may survive and grow to produce toxins subsequent to manufacturing or domestic heating steps. Such microorganisms include species of the genus Clostridium.
Conventional fully dried pasta products (i.e., dried pasta with about 10 or less percent moisture) are generally stable with regard to such microorganisms when stored at ambient temperatures. Refrigerated pastas are available both unfilled and filled. For refrigerated pastas, the moisture content is maintained at about 30 percent or less in order to control microorganisms. Generally such unfilled refrigerated pastas are stable for up to about 150 days at refrigeration temperatures; refrigerated pastas filled with a high moisture filling generally have shorted shelf lives (generally less than about 120 days at refrigeration temperatures). Both fully dried and refrigerated pasta must be cooked in boiling water to fully hydrate (i.e., increase moisture content up to about 50 percent) the pasta prior to consumption.
Nisin is a peptide-like antibacterial substance produced by microorganisms such as Lactococcus lactis subsp. lactis (formerly known as Streptococcus lactis). Its structure is illustrated in U.S. Pat. No. 5,527,505 to Yamauchi et al. The highest activity preparations of nisin contain about 40 million International Units (IU) per gram. Commercial preparations of nisin are available. For example, one commercial preparation, NISAPLIN(trademark) containing about 1 million IU per gram is available from Aplin and Barrett Ltd., Trowbridge, England; another commercial preparation, CHRISIN(trademark), containing about 1 million IU per gram is available from Chr. Hanson A/S (Denmark). Nisin has no known toxic effects in humans. It is widely used in a variety of prepared dairy foods. Experimental use in preserving other foods has also been reported. Details on these applications are provided below.
A number of efforts have been reported since 1975 directed to reducing uncoupled acid production in dairy fermentations by controlling the post-fermentation acidification of yogurt. In some of these studies, a nisin producing culture was introduced in an attempt to inhibit these effects. Kalra et al. (Indian Journal of Dairy Science, 28: 71-72 (1975)) incorporated the nisin producing culture Streptococcus lactis (now known as L. lactis subsp. lactis) along with the yogurt culture before fermentation. Others introduced nisin in milk prior to fermentation (Bayoumi, Chem. Mikrobiol. Technol. Lebensm., 13:65-69 (1991)) or following fermentation (Gupta et al., Cultured Dairy Products Journal, 23: 17-18 (1988); Gupta et al., Cultured Dairy Products Journal, 23: 9-10 (1989)). In all cases, the rate of post-fermentation acidification was only partially inhibited by these treatments and the yogurt continued to become more acidic throughout its shelf life.
In U.S. Pat. No. 5,527,505, yogurt was produced from raw milk by incorporating a nisin-producing strain, Lactococcus lactis subsp. lactis, along with the traditional yogurt culture consisting of Streptococcus salivarius subsp. thermophilus (ST) and Lactobacillus delbrueckii subsp. bulgaricus (LB). This patent teaches that the lactococci are needed to secrete the nisin, whose effect is to retard the activity of ST and LB. The resulting yogurt therefore contains the lactococci used to produce the nisin. Nonetheless, the acidity of yogurt containing the nisin-producing bacteria increased by 64 to 96 percent in 14 days in various experiments inoculated with differing amounts of L. lactis subsp. lactis, compared to the initial acidity at the completion of fermentation. Other studies (Hogarty et al., J. Fd. Prot., 45:1208-1211 (1982); Sadovski et al., XX International Dairy Congress, Vol. E: 542-5-44 (1978)) also noted acid production and development of bitterness at low temperature by some mesophilic starter lactococci in dairy products.
In U.S. Pat. No. 5,015,487, the use of nisin, as a representative of the class of lanthionine bacteriocins, to control undesirable microorganisms in heat processed meats is disclosed. In tests involving dipping frankfurters in nisin solutions, the growth of L. monocytogenes was effectively inhibited upon storage at 40xc2x0 F.
Chung et al. (Appl. Envir. Microbiol., 55, 1329-1333 (1989)) report that nisin has an inhibitory effect on gram-positive bacteria, such as L. monocytogenes, Staphylococcus aureus, and Streptococcus lactis, but has no such effect on gram-negative bacteria such as Serratia marcescens, Salmonella typhimurium, and Pseudomonas aeruginosa when these microorganisms are attached to meat.
Nisin has been added to cheeses to inhibit toxin production by Clostridium botulinum (U.S. Pat. No. 4,584,199). This patent discloses a detailed example in which chicken frankfurter components are shown to require the presence of both added nitrite and added nisin in order to prevent or delay botulinum toxin production when challenged with C. botulinum. 
Nisaplin(trademark) has been found to preserve salad dressings from microbiological contamination, such as challenge by Lactobacillus brevis subsp. lindneri, for an extended shelf life period (Muriana et al., J. Food Protection, 58:1109-1113 (1995)).
More recently, whey from nisin-producing cultures has been used to preserve and stabilize food compositions, including fermented dairy products, mayonnaise-type spreads, cream cheese products, meat compositions, and meat/vegetable compositions. These uses of whey from nisin-producing cultures are described in U.S. Pat. No. 6,136,351 (Oct. 24, 2000) entitled xe2x80x9cStabilization of Fermented Dairy Compositions Using Whey from Nisin-Producing Culturesxe2x80x9d; and applications entitled xe2x80x9cStabilization of Mayonnaise Spreads Using Whey from Nisin-Producing Culturesxe2x80x9d, U.S. patent application Ser. No. 09/386,680, filed Aug. 31, 1999; xe2x80x9cStabilization of Cream Cheese Compositions Using Nisin-Producing Culturesxe2x80x9d, U.S. patent application Ser. No. 09/386,795, filed Aug. 31, 1999; xe2x80x9cStabilization of Cooked Meat Compositions Using Whey From Nisin-Producing Culturesxe2x80x9d, U.S. patent application Ser. No. 09/386,793, filed Aug. 31, 1999; and xe2x80x9cStabilization of Cooked Meat and Vegetable Compositions Using Whey From Nisin-Producing Culturesxe2x80x9d, U.S. patent application Ser. No. 09/779,712, filed Feb. 8, 2001. Each of these applications, which are owned by the same assignee as the present invention, are incorporated by reference in their entireties.
There remains a need for fully cooked refrigerated pasta compositions and procedures related to such fully cooked refrigerated pasta compositions that inhibit the growth of pathogenic microorganisms, and the production of toxins by them, using natural or innocuous ingredients. There also remains a need for fully cooked, refrigerated, and filled pasta compositions and procedures related to such fully cooked, refrigerated, and filled pasta compositions that inhibit the growth of pathogenic microorganisms, and the production of toxins by them, using natural or innocuous ingredients. The present invention addresses these needs.
This invention relates to stabilization of cooked pasta compositions against the development of toxins from pathogenic bacterial contaminants. The stabilized pasta compositions are attained by the incorporation of nisin-containing cultured whey derived from a nisin-producing culture in the pasta dough. The cooked pasta compositions of this invention, which include both filled and unfilled pasta compositions, are stable at refrigeration temperatures for 90 days or longer, and preferably for 120 days or longer, and require no further cooking (i.e., the pasta is fully hydrated and only requires warming before serving).
In an important embodiment, the nisin-containing cultured whey is obtained from the fermentation of a fortified cheese whey composition using a nisin-producing microorganism. In an alternative embodiment, the nisin-containing cultured whey is prepared by inoculating a pasteurized dairy composition with a culture of a nisin-producing microorganism, incubating the composition until the pH attains a value between about 6.2 and about 4.0 and a whey and curd mixture is formed, and separating the whey from the whey and curd mixture to give the separated whey which is the nisin-containing cultured whey.
The invention also provides a method of making stabilized fully cooked pasta compositions which are stable at refrigeration temperatures. The invention additionally provides a method of inhibiting the growth of a pathogenic microorganism in fully cooked pasta compositions during storage at refrigeration temperatures.
In important embodiments of the preparation and methods of the invention, the growth of microorganisms chosen from the group consisting of Clostridium botulinum, C. perfringens, Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus, and Enterococcus faecalis is inhibited, and in a more preferred embodiment, the inhibited microorganism is C. botulinum. 
The pasta of the present invention is prepared from pasta dough comprising about 55 to about 80 percent high protein wheat flour, about 1 to about 5 percent wheat gluten, 0 to about 20 percent egg product, 0 to about 3 percent dough conditioner, sufficient nisin-containing cultured whey to provide at least about 150 IU nisin/g pasta dough, and sufficient water to provide a total moisture content of about 25 to about 35 percent. Of course, the amount of nisin-containing cultured whey required will depend on the specific nisin-containing cultured whey; generally about 1 to 15 percent of the nisin-containing cultured whey will provide the desired level of nisin. More preferably, the pasta of the present invention is prepared from pasta dough comprising about 60 to about 70 percent high protein wheat flour, about 1 to about 4 percent wheat gluten, 0 to about 20 percent egg product, 0 to about 2 percent dough conditioner, sufficient nisin-containing cultured whey to provide about 200 to about 1200 IU nisin/g pasta dough, and sufficient water to provide a total moisture content of about 25 to about 35 percent. Even more preferably, the pasta of the present invention is prepared from pasta dough comprising about 62 to about 68 percent high protein wheat flour, about 2 to about 3.5 percent wheat gluten, 8 to about 12 percent egg product, about 0.01 to about 1 percent dough conditioner, sufficient nisin-containing cultured whey to provide about 300 to about 700 IU nisin/g pasta dough, and sufficient water to provide a total moisture content of about 28 to about 32 percent. Generally, the pasta dough contains about 25 to about 35 percent total moisture, and more preferably about 28 to about 32 moisture; the relative amounts of the ingredients, especially the nisin-containing cultured whey, egg product, and any added water, can be adjusted to obtain the desired moisture content.
Both unfilled and filled pasta can be prepared using the compositions and methods of this invention. Pasta with or without pasta sauces can also be prepared using the compositions and methods of this invention. Preferably, such fillings and sauces are prepared using the same or similar nisin-containing cultured whey as used to prepare the pasta dough. The final pasta products produced by the method of this invention generally contain about 40 to about 65 percent moisture, and preferably about 50 to 60 percent moisture. In spite of these relatively high moisture levels, the final pasta products of the present invention are stable at refrigeration temperatures for 90 days or longer, and preferably for 120 days or longer.